Workaround for offset of linked collection? (Blender 2.8)
TL;DR: Set offset for a corresponding source collection in properties>object>collections  to control where collection will be placed with respect to empty when collection is instanced 

It is possible to provide the offset for a selected collections in source file. Offsets can be set for a source collection in Collections Panel of Object Tab of Properties editor 

Properties &gt; Object Properties &gt; Collections




If location of collection in source file is 4 units in x axis, then set offset of x (in properties>Object> collections) 4 units. By setting offset we can control how far collection instance will be with respect to it's parent empty(also called Instancer). 

Where new collection instances can be create by using add menu or by setting collection in instancer panel of empty object


Collection are the powerful feature introduced in blender 2.8. Blender supports linking nested collections as well. Instancing new collection is equivalent to adding new empty followed by choosing desired collection in instancing panel of object properties. 


For collections in action and workflow check the following video from Blender Conference
Creating blender demos glowing tigers and tortured creatures - Daniel Bystedt